Electronic ballast for HID lamps with active lamp power control

a technology of electronic ballast and hid lamp, which is applied in the direction of electric variable regulation, process and machine control, instruments, etc., can solve the problems of reducing the life of the lamp, requiring several minutes or longer to restart the lamp, and affecting the operation of the lamp. to prevent the reduction of the life of the high-pressure discharge lamp

Inactive Publication Date: 2013-01-01
PANASONIC CORP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

The solution effectively prevents ballast breakdown and extends the life of HID lamps by maintaining appropriate load current control, even when load voltages of positive and negative polarities are significantly different, thus stabilizing lamp operation and reducing the risk of failure.

Problems solved by technology

However, when the load voltage values of positive and negative polarities are largely different (for example, in a half-wave discharge or lamp rectification state), the target values of the load currents are different in the positive and negative polarity periods, and therefore a deviation is inevitably caused with respect to a target value of the load current in any one of the polarities.
Accordingly, there is concern for failure of the ballast or reduction in life of the lamp.
In addition, after the lamp is started, it may take several minutes or longer to restart the lamp due to an increase of a gas pressure inside the lamp.

Method used

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  • Electronic ballast for HID lamps with active lamp power control
  • Electronic ballast for HID lamps with active lamp power control
  • Electronic ballast for HID lamps with active lamp power control

Examples

Experimental program
Comparison scheme
Effect test

first embodiment

[0044]FIG. 1 is a circuit diagram of an electronic ballast according to the present invention. The ballast 4 includes a full-wave rectifying circuit DB, a step-up or boost chopper circuit 5 and an inverter circuit 1. The full-wave rectifying circuit DB can be a diode bridge circuit connected to a commercial AC power source Vs to rectify an AC voltage thereof and output a pulsating voltage. The step-up chopper circuit 5 receives the rectified voltage output of the full-wave rectifying circuit DB and outputs a stepped-up DC voltage Vdc. The inverter circuit 1 is controlled to step down the DC voltage Vdc and supply appropriate power and a rectangular wave AC voltage to the high-pressure discharge lamp DL connected to inverter output terminals. In addition, during lamp starting, a high frequency voltage is generated for driving a resonant starting voltage generation circuit 3.

[0045]The following describes one embodiment of the step-up chopper circuit 5. An input capacitor C1 is connect...

third embodiment

[0065]Therefore, in the third embodiment, the comparison and selection operation is started when the load voltages of both positive and negative polarities detected by the load voltage detection circuit 21 exceed a prescribed constant value. This prescribed constant value indicates load voltage in a way of transition from an unstable discharge state immediately after starting the lamp DL to a stable discharge state at a time of rated lighting. As one example, the comparison and selection operation may be started when the load voltage exceeds about 50V.

[0066]Although the comparison and selection operation of the load voltage is started when the load voltages of both positive and negative polarities exceed a prescribed constant value in consideration of preventing output power from exceeding a prescribed value in the third embodiment, it may be possible to select a polarity having a larger target value of load current in order to improve half-wave discharge, etc., as described in the ...

fourth embodiment

[0067]FIG. 7 shows operation of the present invention. The ballast circuit configuration may be the same as that shown in FIG. 1. In the embodiment of FIG. 7, further explanation is made with regard to timing of starting the comparison and selection operation. In this embodiment, operation of the comparison and selection is started after a prescribed time elapses after the lamp is started. This prescribed time indicates a time period in a way of transition from an unstable discharge state immediately after starting the lamp DL to a stable discharge state at a time of rated lighting. As one example, the comparison and selection operation of may be started when about three minutes elapses after the lamp is started.

[0068]In the fourth embodiment, although the comparison and selection operation is started after a prescribed time elapses after starting in consideration of preventing output power from exceeding a predetermined value, the polarity having a larger target value of load curre...

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Abstract

An electronic ballast includes a ballast control circuit controlling an inverter circuit to supply a rectangular wave AC power to a high-pressure discharge lamp. The ballast control circuit includes a load voltage detection circuit adapted to detect load voltages of both positive and negative polarities applied to the lamp, a comparison and selection circuit adapted to compare the detected load voltages of the positive and negative polarities and select one of the positive and negative polarities, and a switching control circuit adapted to use the load voltage of the polarity selected by the comparison and selection circuit for controlling load current in one cycle after a period of detecting the load voltages of both the positive and negative polarities.

Description

[0001]A portion of the disclosure of this patent document contains material that is subject to copyright protection. The copyright owner has no objection to the reproduction of the patent document or the patent disclosure, as it appears in the U.S. Patent and Trademark Office patent file or records, but otherwise reserves all copyright rights whatsoever.CROSS-REFERENCES TO RELATED APPLICATIONS[0002]This application claims benefit of the following patent application(s) which is / are hereby incorporated by reference: Japan Patent Application No. 2009-104493, filed Apr. 22, 2009.STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT[0003]Not ApplicableREFERENCE TO SEQUENCE LISTING OR COMPUTER PROGRAM LISTING APPENDIX[0004]Not ApplicableBACKGROUND OF THE INVENTION[0005]The present invention relates to electronic ballasts for powering high-intensity and a high-pressure discharge (HID) lamps such as high-pressure mercury and metal halide lamps, and to lamp fixtures using the same....

Claims

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Application Information

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Patent Type & AuthorityPatents(United States)
IPC IPC(8): H05B41/26
CPCH05B41/2888H05B41/2928Y02B20/202Y02B20/00
InventorMATSUZAKI, NOBUTOSHI
OwnerPANASONIC CORP